I don't think history backs you. Reed isn't a young closer on his last year, he's got essentially 5 years of control, two of which are not even arbitration eligible. There probably aren't' a lot of cases of closers with his experience level and contract situation getting traded. But it's not because players in his situation are worthless, it's because they're so valuable; teams don't normally trade cost controlled players in key positions, short of a fire sale. Reeds not only valuable, he's probably got more value than anyone other than Sale, and in some ways more considering his contract status.

Two blown save in a week, two blown saves all season. The dude is 19 for 21 to start this year after going 29 of 33 in his rookie year. He'd be closer on more than 75% of teams out there.

You are right that teams acquire relief pitchers at the deadline. Teams acquire relief pitchers on waivers. Teams like good young arms. Teams like arms they can depend on situationally. But they don't pay much for them. Relief pitchers acquired late in the season were a big reason the Giants won the 2010 World Series, and they were smart, cheap moves.

Relief pitchers don't have the sort of mid-season trade value you are projecting. Closers in particular have a tendency to flame out, and every major league GM knows that because every major league GM has seen that.

If a team made a strong offer for Reed, I have no doubt the White Sox would trade him. Nate Jones has the skills that might make him a strong closer. But if you are the Tigers in need of a closer because Valverde falters sometimes, blowing two saves since May 31, you aren't going to make a big offer for Addison Reed, who since June 2 has given up two game-tying home runs while one strike away from preserving wins. The sorts of problems Tigers management is seeing Valverde have are not much different from what other teams are seeing in Reed.